In certain apparatus, such as in "Toroidal Z-Pinch" devices, it is essential to have a fast-acting, low-inductance, metal-to-metal crowbar type switch. Frequently, there is a minimum amount of space available for such switches because of space availability within the machine into which such a switch must be fitted. Consequently, there is a need for small switches which are self contained and in fact, quite dissimilar to the exploding foil switches of the prior art. A typical prior art foil switch is shown in D. L. Call, "Engineering Problems of Fusion Research," Los Alamos Scientific Laboratory Report, LA4250 (1969), a copy of which is attached hereto. The foil switches, while at times being desirable, require large and elaborate clamping mechanisms as well as complex individual capacitance discharge systems. Their use is frequently restricted by their environmental requirements, making their use impractical in many situations. A high-explosive driven crowbar switch seems to supply the answer to these problems.